Studies of the absorption, distribution, metabolism and excretion of a series of four 14C-labeled aromatic amines, p-nitroaniline, diphenyl guanidine, 2,4-dinitroaniline, and 4-chloro-2-nitroaniline in the rat indicate that clearance rates vary with compound, but that each compound is readily absorbed, rapidly metabolized and excreted in the form of several metabolites. Excretion of most parent compounds prior to metabolism is minimal. These compounds do not appear to be accumulated to a significant extent in any tissue, possibly due to the fact that they are rapidly metabolized. Within a few hours after administration most of the dose retained by the body was in the form of metabolites. These compounds were eliminated in both urine and feces, and whole body half-lives for each compound was less than 1 day. Additional studies of these and other aromatic or heterocyclic amines will provide a better understanding of the importance of chemical structure to metabolism, disposition and persistence of this class of compounds.